As a sensor for analyzing ingredients contained in a liquid or the like, a sensor for detecting light of a specific wavelength has already been used. The sensor irradiates a liquid under measurement with light emitted from a light source, such as an LED, and measures a transmitted, scattered or reflected amount in terms of each specific wavelength. Subsequently, the ingredients are identified by comparing the measurement result with intrinsic absorption and scattering characteristics of the targets of analysis as a function of wavelength.
On the other hand, as a result of the advance in information and telecommunication technology and the expansion of network infrastructure in recent years, there has been a new trend in sensor usage such as that for energy conservation in building air conditioning, for water quality management in waterworks and for grasping consumer behavior, where a sensor device with small size and high sensitivity is demanded, for the purpose of realizing a system which can make simultaneous use of a large number of sensors.
Related technologies are disclosed in Patent Literature 1 to Patent Literature 5.
An optical sensor described in Patent Literature 1 is composed of a microlens array, a color filter array and a sensor array. Light emitted from a light source is condensed by the microlens array, and accordingly becomes incident on the color filter array. Out of the light incident on the color filter array, only a specific wavelength component is transmitted by each filter of the color filter array, in accordance with the filter's transmission characteristics. Light transmitted by the color filter array becomes incident on the sensor array. From the sensor array, a voltage is outputted in accordance with the incident light amount.
Patent Literature 2 and Patent Literature 3 disclose a microlens array composed of a plurality of convex microlenses each arranged such that at least part of its periphery overlaps with neighboring microlenses.
Patent Literature 4 and Patent Literature 5 disclose a microlens array constructed by arranging a plurality of microlenses.